Grooves for edge and hot spot compensation in chemical mechanical polishing

A polishing system, comprising:

• a rotatable platen to support a polishing pad that has a polishing-rate adjustment groove that is concentric with an axis of rotation of the platen;
• a first dispenser to deliver a polishing liquid onto the polishing pad;
• a second dispenser to deliver a coolant, a dilutant, or both, directly into the polishing-rate adjustment groove such that a polishing rate is reduced in an annular zone of the polishing pad that is positioned radially inward of the polishing-rate adjustment groove, and wherein the annular zone surrounds a central zone of the polishing pad in which a polishing rate is not substantially affected by the coolant, dilutant, or both;
• a carrier head to hold a substrate against the polishing pad, the carrier head laterally movable across the polishing pad;
• an actuator to move the carrier head;
• and
• a controller coupled to the actuator and configured to cause the actuator to oscillate the carrier head and substrate laterally across the polishing pad such that
• for a first duration cause the actuator to position a central portion of the substrate and an edge portion of the substrate over the central zone of the polishing pad such that the central portion of the substrate and the edge portion of the substrate are polished for the first duration by the central zone of the polishing pad, and
• for a second duration cause the actuator to position the central portion of the substrate over the central zone of the polishing pad and an angularly extending section of the edge portion of the substrate over the annular zone such that the central portion of the substrate is polished for the second duration by the central zone of the polishing pad and the edge portion of the substrate is polished for the second duration by both the central zone of the polishing pad and the annular zone so as to reduce a polishing rate of the edge portion.